The upstream sector includes the searching for potential underground or underwater crude oil and natural gas fields, drilling of exploratory wells, and subsequently drilling and operating the wells that recover and bring the crude oil and/or raw natural gas to the surface. [3] there has been a significant shift toward including unconventional gas as a part of the upstream sector, and corresponding developments in liquefied natural gas (LNG) processing and transport.

Upstream Industry has traditionally experienced the highest quantum of Mergers, Acquisitions and Divestitures. M&A activity for upstream oil and gas deals in 2012 totaled $254 billion in 679 deals.[4] A large chunk of this M&A, 33% in 2012, was driven by the Unconventional/shale boom especially in the US followed by the Former Soviet Union and Canada.

The aggregate value of Upstream E&P assets available for sale (Deals in Play) reached a record-high of $135 billion in Q3-2013.[5] The value of Deals in Play doubled from $46 billion in 2009 to $90 billion in 2010. With ongoing M&A activity the level remained almost the same reaching $85 billion in Dec-2012. However, the first half of 2013 saw approximately $48 billion of net new assets coming on the market. Remarkably, the total value of Deals in Play in Q3-2013 nearly tripled over 2009 at $46 billion, in less than four years.